1. Field of the Invention
The present invention relates to a tension mounting system and assembly whereby a flexible sheet material may be suspended in a taut condition from a generally planar support surface. The mounting system and assembly of the present invention is particularly suitable for use in signs displaying advertising material, such as billboards, signboards, and the like.
2. Description of the Prior Art
Display signs have been used for a variety of purposes and in a variety of applications, typically for promoting a business or a product. Conventional billboards generally comprise a planar rigid support surface, or a plurality of such surfaces mounted adjacent one another, upon which the advertising message is painted. Alternatively, the advertising material may be painted or printed on paper or another sheet-like material which is then affixed to the planar rigid support surface, typically by means of adhesives. In many cases, the billboard comprises a freestanding structure mounted on the ground or on a building or the like, and it may be illuminated by spotlights, or the like, to provide visibility during the nighttime. In some cases, advertising material is applied directly to the surfaces of a building structure itself because the building structure cannot support the weight of a billboard support structure. These types of conventional billboards are very expensive to erect and maintain because preparation and maintenance, in particular, are labor intensive operations. The appearance of conventional billboards is also apt to deteriorate rapidly due to weather conditions such as sun, precipitation, changes in temperature, and the like.
Signs comprising a substantially rigid sheet of transparent or translucent material upon which an advertising message has been applied have also been utilized, generally by mounting them in a cabinet and illuminating the sheet material bearing the advertising message from inside the cabinet. These types of display signs generally exhibit less deterioration due to weather conditions, but the size of the display sign is quite limited, since transport and installation of a large, substantially rigid sheet is impracticable. In addition, these materials exhibit at least some resiliency, which limits the practical dimensions of the sign, and tends to result in distortion or bowing of the sign due to the weight of the material and due to adverse weather conditions, such as high winds.
Recent innovations in the advertising industry include the use of a flexible, fabric-like sheet material which is light, relatively impervious to weather, and may be illuminated from behind to provide an attractive and effective display. This material is preferably suspended in a taut condition to provide a planar display surface. The costs associated with installation and maintenance of display signs comprising a flexible sheet material are generally less than those associated with conventional signboards and billboards, since the advertising message may be applied at a central location, and the sheet material may be rolled or folded for convenient transport to the display location. The flexible fabric-like sheet material may be applied over or suspended from a conventional billboard support surface or a building support structure.
Means for mounting and/or framing flexible paper and synthetic sheet-like materials are known to the art. U.S. Pat. No. 2,212,313 teaches a display panel wherein a flexible, replaceable cover is mounted to a rigid rail at each longitudinal edge, and the longitudinal edges are wrapped around upright tubular structures and anchored to cross members by means of springs. U.S. Pat. No. 2,533,565 teaches a display frame for retaining a flexible display panel in a taut condition generally parallel to a backing board by means of spring clips along one edge and rigid clips along the opposite edge. U.S. Pat. No. 3,591,940 teaches a supporting frame for releasably clamping flexible sheet materials, such as posters, to the frame means. The poster is fastenable to opposite frame members by clamp means and a spring may be wedged between the frame members to provide the desired tension. U.S. Pat. No. 3,758,972 teaches a sign housing with a removably mounted sign panel wherein the edges of the sign sheet and a protective cover sheet are retained between nesting members of the panel frame. U.S. Pat. No. 3,830,278 teaches a modular canvas stretcher wherein canvas is fastened to the stretcher frame comprising rigid, mitered elongated members having longitudinal channels for retaining bracket members and bracing members. U.S. Pat. No. 4,233,765 teaches a peripheral framework for suspending flexible sheet materials over a central open area. The peripheral framework is provided with a channel for receiving a flexible strip member, by which the flexible material is engaged between the channel and the strip member.
U.S. Pat. No. 4,317,302 teaches a sign cabinet for outdoor signs comprising a support frame with clamp assemblies for retaining a flexible sign face under tension. U.S. Pat. No. 4,452,000 teaches an illuminatable sign and framework housing therefor, wherein a sheet of flexible, light-transmitting material extends across and covers an opening, and bolts secure a peripheral marginal portion of the sheet by adjustably tensioning the sheet across the opening. U.S. Pat. No. 4,372,071 teaches a fabric faced billboard wherein air pressure is applied from behind the fabric to smooth the fabric and provide a continuous, slightly curved display face.
U.S. Pat. No. 4,265,039 teaches a framework for suspending a fabric display face and a clamp assembly for selective adjustment of fabric tension. The '039 patent teaches that prior art clamp assemblies required spaced holes to be punched in the fabric display through which bolts of the clamp assemblies were passed. The clamp assemblies were tightened around the fabric by means of a first nut, and the fabric was then tensioned by means of a second nut drawing the suspended clamp toward the mounted bracket. This system is undesirable from the standpoint that a plurality of holes are required in the fabric sign at prescribed intervals, and the fabric sign is prone to tearing during installation. In addition, multiple adjustments of the multiplicity of clamp assemblies to first tighten the clamp assembly around the fabric and then tension the fabric, is tedious and time consuming. The '039 patent teaches a fastening assembly having upper and lower support elements joined between corresponding opposite ends by respective side support elements. A hinge element is affixed to at least one of the support elements, and a hinge pin to which a marginal portion of the fabric is coupled may undergo limited rotation in conjunction with the hinge element to provide selective adjustment of the tension induced in the fabric.
U.S. Pat. No. 4,657,062 teaches an adjustable clamping system for tensioning and locking a flexible tarp. The '062 patent teaches a roll bar for fastening an edge of the flexible tarp to the clamping means. Roll bars of this type having a groove for retaining an enlarged or supported edge of the flexible tarp may be used in the practice of the present invention.
It is evident from the above recitation of prior art patents that the use of flexible sheet materials for outdoor displays and signboards is known, and that a variety of support structures and tensioning mechanisms has been proposed. None of the prior art systems, however, provides satisfactory and selective tensioning of the flexible sheet-like material in combination with a simplified and convenient assembly technique.